Polymerization Of Dicyclopentadiene Research Articles

The self-healing investigations on fiber-reinforced polymer composites through a novel compartmented microcapillary approach

This paper presents the experimental self-healing investigations on fiber-reinforced polymer (FRP) composites using a novel in-situ healing approach. During the preparation of polymer composites, the monomer Dicyclopentadiene (DCPD) was embedded as the healing agent. The compartment hollow glass microcapillaries were used to serve the localized distribution of the healing agent. To determine the viability of the proposed microcapillary approach, several flexural tests were conducted to initiate the damage and subsequent realization of self-repair activity. The healing was initiated through the polymerization of DCPD in the presence of Grubb’s catalyst (first and second generation). Once healed, the specimens were tested cyclically to evaluate the recovery of flexural strength. A post-failure healing efficiency as high as 72% has been observed. SEM and XRD investigations have been conducted for the microstructural investigations. These investigations support the potential applications of the proposed concept of embedding the bulk with the microcapillaries.

Fabrication and Characterization of Solid Composite Yarns from Carbon Nanotubes and Poly(dicyclopentadiene).

In this report, networks of carbon nanotubes (CNTs) are transformed into composite yarns by infusion, mechanical consolidation and polymerization of dicyclopentadiene (DCPD). The microstructures of the CNT yarn and its composite are characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and a focused ion beam used for cross-sectioning. Pristine yarns have tensile strength, modulus and elongation at failure of 0.8 GPa, 14 GPa and 14.0%, respectively. In the composite yarn, these values are significantly enhanced to 1.2 GPa, 68 GPa and 3.4%, respectively. Owing to the consolidation and alignment improvement, its electrical conductivity was increased from 1.0 × 105 S/m (raw yarn) to 5.0 × 105 S/m and 5.3 × 105 S/m for twisted yarn and composite yarn, respectively. The strengthening mechanism is attributed to the binding of the DCPD polymer, which acts as a capstan and increases frictional forces within the nanotube bundles, making it more difficult to pull them apart.

Synthesis and Porous Structure of Addition Polymer Based on Dicyclopentadiene

A simple two-stage scheme is proposed for the synthesis of a new porous polymeric material based on dicyclopentadiene, an industrial product and one of the most accessible derivatives of norbornene. The selective addition polymerization of dicyclopentadiene, a bifunctional monomer, proceeds via opening of only one endocyclic double bond and the subsequent hydrogenation of the synthesized product makes it possible to obtain a saturated polymeric material with a high specific surface area (425 m2/g). The porous structure of the hydrogenated addition polydicyclopentadiene is studied in comparison with a similar polymer before hydrogenation using low-temperature nitrogen adsorption/desorption and X-ray powder diffraction. It is shown that the polymeric material obtained has a high thermal stability.

Synthesis of polydicyclopentadiene using the Cp2TiCl2/Et2AlCl catalytic system and thin-layer oxidation of the polymer in air.

The polymerization process of dicyclopentadiene using a multicomponent catalytic system based on bis(cyclopentadienyl)titanium dichloride and diethylaluminum chloride was studied. It was demonstrated that the application of an excess of the aluminum component leads to the formation of stable charged complexes of blue discoloration, which initiate cationic polymerization of dicyclopentadiene. Unstabilized thin layers of obtained polydicyclopentadiene undergo oxidation and structuring under atmospheric oxygen. Oxidation of polydicyclopentadiene films in air occurs slowly during several weeks and can be determined by the increase of carbonyl and hydroxyl adsorption bands in infrared spectra. Along with oxidation, cross-linking processes occur in polymers, which lead to a change in physical parameters of the layers, and more precisely to a decrease in the permeability of atmospheric oxygen through the layers. Consequently, this leads to the transition of the oxidation from a kinetic mode into a diffusive mode. Such structural changes do not occur in a polymer that was stabilized by adding an antioxidant.

Synthesis and Characterization of a Novel Interpenetrating Polymer Networks of Polydicyclopentadiene/Polystyrene

Novel interpenetrating polymer networks (IPNs) of Polydicyclopentadiene/Polystyrene (PDCPD/PS) were prepared by in-situ polymerization using Ziegler-Natta and peroxide as double catalytic systems. The structure of PDCPD/PS alloy was characterized by Soxhlet extraction, infrared spectrum (IR) and scanning electron microscope (SEM). The results showed that the polymerization of dicyclopentadiene (DCPD) was facilitated in the presence of styrene and the rate of polymerization as well as the conversion of PDCPD was improved with styrene content. The strong IR absorption peaks of PS indicated high penetration of PS within PDCPD networks, and in the process forming IPNs. There were no obvious traces of PS in the alloy brittle fracture, which prepared in liquid nitrogen and was etched by toluene. This result also demonstrated that PS was dispersed in molecular level in the polymer alloy networks and it tangled with PDCPD. The measurements mechanical properties showed that the tensile strength of the polymer alloy was improved with styrene content. This may be due to homogeneous dispersion of PS in the IPNs. The synergistic effect of PS and PDCPD also played a part in enhancing the mechanical properties of polymer alloy.

Diffusion and Flow Across Nanoporous Polydicyclopentadiene-Based Membranes

We report gas and liquid transport measurements through membranes that have 40% voids made of 14 nm pores. A reactive polylactide-polynorbornenylethylstyrene block polymer is used as a structural template in the polymerization of dicyclopentadiene during the membrane formation process. After the membrane is cast, the pore structure is formed by etching the polylactide component using dilute aqueous base. The pore structure is isotropic; therefore, there is no need for special alignment techniques. Knudsen diffusion experiments and water flow experiments show pores with a tortuosity of 1.81 and a size of 14 nm, a diameter consistent with nitrogen adsorption and small-angle X-ray scattering measurements. These membranes are effective for ultrafiltration, with molecular weight cutoffs (MWCO) consistent with theoretical predictions with no adjustable parameters. These MWCO's can be tuned by changing the size of the constituent blocks in the templating copolymer.

Macroporous poly(dicyclopentadiene) beads

AbstractMacroporous poly(dicyclopentadiene) beads have been produced via chemically induced phase separation in suspension polymerization. Phase separation is promoted by the enthalpic and entropic changes induced by the polymerization of dicyclopentadiene. By using poly(1,2‐butylene glycol) monobutyl ether (Mn 500 g/mol), which is not soluble in the suspending medium, as the porogen, the stabilized droplets of the monomer/porogen mixture can be considered microreactors in which both polymerization and phase separation occur, resulting in solid, biphasic microspheres. The porogen is then extracted with methanol and the particles are finally dried. The resulting macroporous crosslinked poly(dicyclopentadiene) beads are analyzed by scanning electron microscopy, mercury intrusion porosimetry, and nitrogen adsorption and are compared with similar bulk samples. Materials containing isolated pores as well as microstructures built with agglomerated particles have been produced. The porous microspheres showed micrometric average pores' access diameters and specific surface areas ranging from 1.3 to 3.1 m2/g. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 407–415, 2005

Synthesis and reactivity of novel ruthenium carbene catalysts. X-ray structures of [RuCl 2(CHSC 6H 5)(P iPr 3) 2] and [RuCl 2(CHCH 2CH 2- C, N-2-C 5H 4N)(P iPr 3)

Two novel classes of very air-stable ruthenium carbene complexes have been developed. The arylthio substituted ruthenium carbenes containing two bulky phosphines are deep purple solids, whereas the 2-pyridylethanyl substituted ruthenium carbene complexes contain only one bulky phosphine and are light-brown colored. One member of each class has been characterized with X-ray crystallography. The metathesis activity of these complexes has been investigated in the polymerization of dicyclopentadiene. Several excellent catalysts were identified. Desired geltimes and initiation temperatures could be easily tuned by changing the substitution pattern on the pendant ligand in the 2-pyridylethanyl substituted ruthenium carbenes.

New catalysts for linear polydicyclopentadiene synthesis

The ring-opening polymerization of dicyclopentadiene (DCPD) may occur in two ways: in the first way the reaction occurs by opening of the norbornene ring, in the second one both rings, norbornene and cyclopentene are involved. The polymerization of DCPD via opening of norbornene moiety implies the utilization of very selective catalytic systems. In our work, several new catalytic systems for synthesis of linear polydicyclopentadiene, derived from WCl 6 and WOCl 4 and organosilicon compounds have been employed. The microstructure of the linear polydicyclopentadiene (prepared from endo-DCPD) was evaluated from IR, and 13 C -NMR spectroscopy, showing that the polymer has prevailingly “ cis” double bond configuration. The thermal behavior has been followed by differential scanning calorimetry. The linear polydicyclopentadiene obtained under these conditions has a glass-transition temperature of 53°C.

The polymerization of dicyclopentadiene: an investigation of mechanism

This contribution presents further information about the mechanism of the cross-linking reaction which occurs during the polymerization of dicyclopentadiene with the classical catalyst, WCl 6/Et 2AlCl ( 1), and the well-defined preformed alkylidene, Mo(N-2,6-C 6H 3- i-Pr)(CHC(CH 3) 2Ph)(OCCH 3(CF 3) 2) 2 ( 2). When the classical system 1 was used as a catalyst, insoluble polymer was formed in all cases. However, when molybdenum catalyst 2 is employed, solution concentration determines whether soluble or insoluble polymer will form. The formation of insoluble material is attributed to an olefin addition process catalyzed by the heat released upon ring-opening metathesis polymerization of the norbornene subunit of the monomer. If the heat is removed from the polymerization system through dilution or by cooling the solution, soluble linear polymer is formed. These results suggest that an olefin addition process is at least partly responsible for the cross-linking reaction that occurs during the polymerization of dicyclopentadiene. All attempts to cross-link oligomers of linear polydicyclopentadiene with the well-defined molybdenum alkylidene 2 resulted in only the recovery of soluble polymer. With the classical catalyst system 1, insoluble material was obtained, which was assumed to be cross-linked through olefin addition. These results disprove the idea that metathesis cross-linking can be induced by a critical chain length or concentration of polydicyclopentadiene. On the contrary, no indication of metathesis cross-linking was observed whatsoever for these polymerization systems.

Polymerization of Dicyclopentadiene: A Tale of Two Mechanisms

Polymerization of Dicyclopentadiene: A Tale of Two Mechanisms

Novel catalysts for the ring‐opening metathesis polymerization of norbornene‐type monomers

AbstractA novel family of metallate compounds has been developed for use in catalyst systems for the ring‐opening polymerization of dicyclopentadiene (DCPD) and other norbornene‐type monomers. Examples of these novel catalyst compounds are the organoammonium isopoly‐and heteropolymetallates. Applications of these metallates in combination with alkylaluminum‐type reducing cocatalysts are found in the production of both solution polymers, and cross‐linked resins from reaction injection molding (RIM). These catalyst systems have significant advantages over prior art catalysts. They are highly soluble in DCPD and other norbornene‐type monomers, thus eliminating the need for a reaction solvent. They also are insensitive to air and moisture, have unlimited shelf‐life in solution in norbornene‐type monomers, and do not function as Lewis acids. The chemistry of these catalyst systems is discussed, along with the benefits they provide to the properties of the final polymer products. © 1993 John Wiley & Sons, Inc.

Polymerization of dicyclopentadiene: A new reaction injection molding system

AbstractDicyclopentadiene was polymerized by reaction injection molding (RIM) using a catalyst system based on WCl6 and diethylaluminium chloride. Ring opening polymerization results in formation of a crosslinked polymer with a high crosslink density. The kinetics of the fast exothermic reaction was followed by the adiabatic temperature rise method. In addition to the “adiabatic” polymerization, isothermal reactions were carried out in a thin mold. The properties of the cured samples were determined by dynamic mechanical measurements, solgel analysis, gas chromatography, mass spectrometry, DSC, and IR spectrometry. Gel fraction, glass transition temperature, content of the unreacted monomer, the modulus, and the degree of swelling were used to characterize the cured samples. The system shows very low critical conversion at the gel point (αc < 0.01) proving a chainwise mechanism of the polymerization. Possible participation of a cationic mechanism is discussed. We found the specific reaction temperature range (T = 100–140°C) for optimum properties of the cured samples. Deterioration of properties (decrease in the crosslinking density, etc.) at a high temperature is a result of a faster deactivation of catalytic centers and a reversibility of the exothermic ring opening polymerization. Reverse cyclodegradation is preferred at a higher temperature.

Structure and Content of Dicyclopentadiene in Ethylene Propylene Dicyclopentadiene Terpolymers

Abstract With the aid of model compounds—derivatives of endo- and exo-dicyclopentadiene—it has been established that a) the 9, 10-double bond (the double bond in the norbornane ring) is involved in the polymerization of dicyclopentadiene with ethylene and propylene, b) dicyclopentadiene, present in the polymerization mixture in the endo-configuration, occurs in the exo-configuration in the polymer chain. The same model compounds enable the dicyclopentadiene content of ethylene propylene dicyclopentadiene terpolymers to be determined by infrared spectroscopic methods. Use is made of the 3045 cm−1 band, which is characteristic of endo-cyclic double bonds in five-membered rings.

Structure and content of dicyclopentadiene in ethylene‐propylene‐dicyclopentadiene terpolymers

AbstractWith the aid of model compounds – derivatives of endo‐ and exo‐dicyclopentadiene – it has been established that: (a) the 9,10‐double bond (the double bond in the norbornane‐ring) is involved in the polymerization of dicyclopentadiene with ethylene and propylene; (b) dicyclopentadiene, present in the polymerization mixture in the endo‐configuration, occurs in the exo‐configuration in the polymer chain.The same model compounds enable the DCPD‐content of ethylene‐propylene‐DCPD terpolymers to be determined by infrared‐spectroscopic methods. Use is made of the 3045 cm−1 band, which is characteristic of endo‐cyclic double bonds in five‐membered rings.